Two-stroke internal combustion engine



Sept. 26, 1933- H. HEINZELMANN TWO-STROKE INTERNAL COMBUSTION ENGINE Filed Dec. 4, 1930 |N\/ENTEI Patented Sept. 26, 1933 UNITED STATES PATENT OFFICE,v

TWO-STROKE INTERNAL COMBUSTION ENGINE i Y Application December 4, 1930', Serial No. 499,933,

' and in Switzerland December 18, 1929 1 Claim.

This invention relates to two-stroke internal combustion engines of the kind having two admission ports or sets of admission ports so arranged as to be successively uncovered by the 5 piston during the expansion stroke.

In two-stroke internal combustion engines in which the scavenging of the cylinder iseffected through sets of admission ports which are successively uncovered by the piston, it has been proposed to form the set of ports last covered by the piston during the compression stroke so that the charge issues therethrough substantially tangentially. With such an arrangement, however, the cross-sectional area of the inlets from the ports is undesirably reduced owing to the tangential arrangement of these ports with the result that the scavenging air has to be forced into the cylinder at such high velocity as to result in an incomplete scavenging on account of this airbecoming undesirably mixed with the combustion products.

In a two-stroke internal combustion engine according to the present invention the admission ports extend over a greater part of the circumference of the cylinder than the exhaust ports and are adapted to be successively uncovered by the stantially concentric with the cylinder axis, while the admission ports first close by the piston during the compression stroke open into the cylinder substantially radially so as to obtain rapid scavenging of the cylinder when the piston 1 is at its lower dead centreand to impart a whirling motion to the air remaining in the cylinder after scavenging.

Three alternative constructions according to the invention are diagrammatically illustrated in the accompanying 'drawing, in which Figures 1, 2 and 3 respectively show the three alternative constructions in sectional elevation,

Figure 4-is a'section' inthe p1ane'IV-IV oi FigureL '9 Figure 5 is a section in the plane V-V of Figure 1,

of Figure 2, i

Figure 7 is a corresponding section to' Figure 6 in the plane VII,-VII of Figure 2, I v Figure 8is a partial section in the plane VIII-'VIII of Figure 3, and

Figure 9 is a partial section in the plane IX-IX of Figure 3. a

In each of the constructions shown the engine 'second cylinder segment is defined by passing comprises a cylinder 1 having a working chamber 2 the upper end of which is closed by a cylinder head or cover 3. Disposed within the. cylinder is a piston 4 adapted to uncover at the end of its expansion stroke two sets of admission ports, the lower set comprising ports 5 situated opposite to exhaust ports 6, and ports 7 arra'ingedbetween the ports 5 and the ports 6, while the upper set comprises ports 9 situated opposite to the exhaust ports 6 and ports 10 disposed between the ports 9 and the ports 6. The supply of air to the ports 5 and 7 can take place freely while that to the ports 9 and 10 is controlled by one or more valves 8. It will be seen that the admission ports occupy a larger proportion of the circumference of the cylinder than the exhaust ports.

In each of the constructions-shown the 1ower series of admission ports arediSposed relatively to the exhaust ports so that they-will be closed on the compression stroke beforethe" exhaust ports are completely closed. ,On the other hand, some at least of the upper set 'of admission ports extend above' the exhaust ports so that they'are 1 maintained open during the compression stroke after the exhaust ports havelbeen closed.

y In the construction shown in Figures 1, 4 and 5 the admission ports 9 and 10 are arranged tangentially while the admission ports 5, '7 are disposed truly radially; the ports 9 being formed so as to'be closed after the exhaust ports 6 during 35 the compression stroke, while the ports 10 are closed substantially simultaneously with the exhaust ports 6.

In the construction shown in Figures. 2, 6 and '7, on the other hand, the ports 9 and 7 enter the cylinder truly radially while the ports 10 enter the cylinder tangentially so that the air enters therethrough in the direction of the arrows indicated at 11 in Figure 2 and at 12 in Figure 6. Inthis way a rapid scavenging of the space im- 5 mediately abovethe piston face is ensured when the piston is at its lower dead centre.

The various port openingsare bestdescribed I with respect to' their locations in the cylinder ,wall, by defining. certain segments of the cylinder 9-. 'in which the orts are laced; If two arallel Figurefi isapartial section in theplane VI--VI p p p planes are passed through the cylinder at right angles to the principal axis thereof, a cylinder.

another of such planes to embrace all. of the top edges ofports 5 and 7, a cylindrical segment is defined in which the ports reside. Similarly, a

such planes to embrace the top and the bottom edges of the admission ports 9 and 10. This second segmentdefines the location of the ports 9 and 10. The ports 9 and 10 are located above the ports 5 and '7, in other words, they are closer to the cylinder head than ports 5 and '7. It is, therefore, apparent that a substantial length of cylinder wall exists between these two groups of admission ports.

In the construction shown in Figures 3, 8 and 9, the ports 9 and 10 are all disposed tangentially while the ports 5 and 7 are disposed truly radially, all the ports 9 and 10 in this construction being so formed that they are closed during the compression stroke after the exhaust ports are closed. The direction of the air entering through the ports 9 and 10 is indicated by the arrows 13 and 14 in Figure 3 and by the arrow 15 in Figure 8, while the path of this air is also shown bythe chain line in Figure 3. This air forms what may be regarded as a gyrating wall enclosing the air admitted through the lower set of admission ports 5 and 7, thus tending to prevent the air entering through the ports 5 from flowing directly across the cylinder and out through the exhaust ports 6.

It will be seen that with a construction according to the present invention the air enteringthe cylinder tangentially acts to cause the air entering radially to follow a prescribed path and thus tends to prevent this air passing directly out through the exhaust ports Without performing useful scavenging work.

Further, the tangential entry of the air through some of the admission ports has the advantage that by directing this air at a suitable angle towards the cylinder head a rotating layer of air in contact with the whole surfaceof the cylinder can be formed so that the rotation of the air and the kinetic energy contained therein is maintained during the compression stroke and assists the atomizing of the fuel.

I claim:

In a two-stroke internal combustion engine the combination comprising a cylinder, a reciprocal piston within said cylinder, a plurality of radial admission ports converging toward the center of the cylinder within a segment of the cylinder, a plurality of tangentially disposed admission ports within a second segment of the cylinder, the second segment disposed above and apart from said first mentioned segment, and a plurality of exhaust ports, portions of which lie Within each of said cylinder segments.

HANS HEINZELMANN. 

